The present invention relates to a control circuit for use in control of peripheral equipment in operational association with a wireless communication appliance, such as a cellular phone, and particularly to a circuit which can function to distinguish the phone being used or not by way of picking up the electromagnetic waves produced by a cellular phone; and further to improve or extend the use of the peripheral equipment thereof.
Wireless communication appliance such as cellular phones have been prevailantly used in recent years in modern cities all over the world. However, there are still some disadvantages associated with such mobile phones. For instance, the general cellular phones must be held by one hand while driving on the road, making the driving rather dangerous. The use of a handfree retainer on which a cellular phone is secured facilitates a driver to use the phone in driving, the phone is usually put in a stand-by state so as to make the use of the phone ready and safe without turning on and off repeatedly the on/off switch, but the noise produced by the voice amplifying circuit and the speaker of the retainer is annoying to a driver. The ringing of a celluar phone in a public place such as a conference room, a theater, or a music hall, or places of the like, is annoying to other people. Moreover, in case a cellular phone is not carried along with the user, ringing of the same will not be heard, especially in a noisy working place.
Generally speaking, a wireless communication appliance such as a cellular phone will automatically send off high frequency signals to a base station on receiving a phone call signal from that station to effect a two-way communication. When not used and in a stand-by mode, the cellular phone will not send off such signal. Based on such feature, the present inventor designed a control circuit which can distinguish if a wireless communication appliance such as a cellular phone is being connected or in use or in a stand-by mode.